Propriospinal myoclonus (PSM) is a rare movement disorder characterized by myoclonic jerks in muscles believed to originate in a myoclonic generator (a “myelomere”) which spread rostrally and caudally to other myotomes above and below the generator. Characteristic features include repetitive, arrhythmic flexion jerks of the trunk, hips, and knees. The signal spreads slowly along propriospinal pathways. Propriospinal myoclonus is idiopathic and has occurred following spinal cord lesions, spinal trauma, drug use, tumor, or infections. However, a specific cause is identified in only 20% of patients. Most affected patients are middle-aged men. In most cases, the myoclonic generator is at the thoracic level. Diagnosis is based on the characteristic clinical features mentioned above and polymyography which shows a slow and orderly rostrocaudal propagation of muscle recruitment.
KeywordsAffected Patient Spinal Cord Lesion Spinal Trauma Symptomatic Therapy Myoclonic Jerk
The video demonstrates that cutaneous stimuli to the back, chest, and abdomen elicit axial myoclonic jerks which cause low-amplitude flexion movements of the hips, neck, trunk, and right sternomastoid muscle while the patient is standing. There is mild scoliosis.
Propriospinal myoclonus.mp4 (MP4 12,197KB)